Electrical activity in white adipose tissue of rat.
Intracellular recording of white adipocytes was performed in an in vitro preparation. Resting potential, input resistance and membrane time constant averaged: -34 +/- 9 mV, 295 +/- 161 M omega, and 58 +/- 19 ms respectively (mean +/- SD, n = 32). Intracellular injection of positive and negative square current pulses elicited membrane voltage responses, characterized by a rectification of the voltage change evoked by positive pulses, and a slow return to baseline at the offset of hyperpolarizing pulses. The amplitude and duration of the slow return to resting potential was dependent on membrane potential, pulse duration, and extracellular K+ concentration. This response was depressed when external Ca2+ was replaced by Co2+, and by external application of 4-aminopyridine. These results indicate that white adipocytes can generate membrane voltage responses which may mostly be a consequence of the activity of ionic channels. The properties of the slow return to baseline suggest that it may be due to a transient K+ current.
Ramírez-Ponce
M P
MP
Departamento de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Spain.
Acosta
J
J
Bellido
J A
JA
D015761:4-Aminopyridine / Q000494:pharmacology; D000273:Adipose Tissue / Q000166:cytology / Q000502:physiology*; D000818:Animals; D003035:Cobalt / Q000494:pharmacology; D004594:Electrophysiology; D004822:Epididymis / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D008839:Microelectrodes; D011188:Potassium / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains
D015221:Potassium Channels; D003035:Cobalt; D015761:4-Aminopyridine; D011188:Potassium